At Richmond Park the LD numbers understated their position

For all the speculation on Labour’s polling collapse there’s only one thing that really matters – how the party performs in actual elections and the first real test of that is May 4th which includes, of course, the Manchester Gorton by-election where they are defending a majority of 24k.

On the face of it Gorton looks impregnable but is it? The Lib Dems have published their latest canvas data for the seat which had them on 31% to LAB’s 51%.

Before you dismiss party canvas data remember what happened when the LDs published similar data ahead of last December’s Richmond Park by-election. This was treated with a high degree of scepticism at the time yet as the chart shows it was extraordinarily predictive of what was going to happen. Those who backed Zac at very tight odds lost.

In Richmond the LD’s main challenge was to attract LAB tactical voters – a task made easier by the way Zac had conducted his London mayoral campaign seven months earlier. The yellows wanted LAB voters to be in no doubt that they could defeat Zac by switching to the LDs and we had the bizarre experience of seeing LAB pick up fewer votes than members in the constituency.

In Manchester Gorton there is a very different challenge – simply trying to get over the fact that they can be credible in a seat where at GE2015 they lost their deposit coming in fifth place with just 4.2% of the vote. The more the battle is portrayed as between red and yellow the greater LD hopes can be.

The 51-31 LAB-LD split is dramatically closer than at GE2015 and suggests a high degree of momentum. An LD victory while not being probable is now starting to look possible

Previous by-election experience is that we can expect a high degree of narrowing between the contenders seen to be in the final two during the close of the campaign. Could, for instance, many of the 9.7% GE2015 CON voters decide that their vote is best used creating another awful embarrassment for Labour?